<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>

    <style>
        *{
            margin: 0;
            padding:0;
        }
        /*       ??vw=335    100vw = 375    335/(375/100)    */
        #banner{
            width: 89.333vw;
            height: 38.4vw;
            margin: 25.867vw auto;
            background: #963;
        }
    </style>
</head>
<body>
    <!-- 
        vw 1vw 等于视口宽度的 1% 
        vh 1vh 等于视口高度的 1%
    -->
    <div id="banner"></div>

</body>
</html>